Deadlocking did not make glass unbreakable. (TV: The Poison Sky) It did, however, make metal incapable of being melted, or at least heated, and could prevent cords and doors from being separated or opened physically. (TV: The Time of Angels)

Adipose Industries Headquarters could be deadlocked, including the doors and windows. The deadlocks there could be activated remotely on command. The Inducer built into the building was said to be triple deadlocked. However, the Doctor was able to open these locks after acquiring the sonic pen of the owner of the building, Miss Foster. (TV: Partners in Crime)

The lock for the cashier's office in a 21st century theatre had a deadlock seal. The Eleventh Doctor found this improbable, considering the technology level of Earth and such an unnecessary need for security. (PROSE: Snowfall)